In rotary fuel pumps driven by an electric motor, it is common to have a motor armature shaft which mounts the armature for rotation. The armature drives a coaxial pump element which is suitably mounted in a surrounding housing. Since these housings are frequently formed of a molded plastic, the journal of bearing for the pump shaft has been in a recess molded into the housing. The problem of a shaft lubrication and support has been approached by making the shaft recess with a polygonal shape, hexagonal or octagonal, the flats of the polygon being in bearing contact with the rotating shaft. This has provided some room for alignment compensation but utilizing the housing material for a bearing has not been entirely successful.
The plastic of the molded end of a pump which has provided the bearing is a glass reinforced thermoplastic polyester. The dimensions of the polygonal hole, for example, hexagonal, has had to be controlled very closely. It is impossible to have an interference fit since this would bind and seize the shaft; if the fit is loose, the pump will produce unacceptable noise. Also, if the pump runs dry of fuel, it will seize up in only two or three minutes.
Some pump designs have utilized brass or sintered bronze bearings molded into a plastic but these bearings have to be lubricated and cannot be run dry.
The present invention contemplates a bearing construction which will have a long life, run quietly, and yet provide the necessary compensation movement for suitable alignment. It is a further object to provide a bearing insert which has an interlock with the main pump end housing and which is shaped to provide an ideal bearing surface.
Other objects and features of the invention will be apparent in the following description and claims in which the invention is set forth together with details to facilitate use of the invention by persons skilled in the art.